Positive electrode active material composite for battery, secondary battery electrode, and secondary battery

Abstract

The present disclosure relates to a positive electrode active material composite which is for a battery and is coated with reduced graphene oxide, and specifically, to a positive electrode active material composite comprising: a core portion including a positive electrode active material; and a shell portion surrounding the core portion. The shell portion includes at least one layer of reduced graphene oxide (rGO), thus making it possible to obtain a secondary battery having excellent electronic conductivity and energy density.

What is claimed is: 
     
         1 . A cathode active material composite for a battery, comprising:
 a core portion that includes a cathode active material; and   a shell portion formed to surround the core portion, wherein the shell portion includes one or more layers of reduced graphene oxide (rGO).   
     
     
         2 . The cathode active material composite for a battery of  claim 1 , wherein the shell portion has an average thickness of 3 nm to 31 nm. 
     
     
         3 . The cathode active material composite for a battery of  claim 1 , wherein a thickness deviation of the shell portion is equal to or less than 55% of the average thickness of the shell portion. 
     
     
         4 . The cathode active material composite for a battery of  claim 1 , wherein the reduced graphene oxide contains 2 to 12% by weight of oxygen (O) relative to the reduced graphene oxide. 
     
     
         5 . The cathode active material composite for a battery of  claim 1 , wherein the reduced graphene oxide has an aspect ratio of 500 to 20,000. 
     
     
         6 . The cathode active material composite for a battery of  claim 1 , wherein the cathode active material composite has a BET specific surface area of 0.3 m 2 /g to 5 m 2 /g. 
     
     
         7 . The cathode active material composite for a battery of  claim 1 , wherein the reduced graphene oxide is dry-coated to form one or more layers and is contained in the shell portion. 
     
     
         8 . The cathode active material composite for a battery of  claim 7 , wherein the reduced graphene oxide is dry-coated using a mechano-fusion device. 
     
     
         9 . The cathode active material composite for a battery of  claim 8 , wherein the reduced graphene oxide is dry-coated by operating the mechano-fusion device at 1,000 to 10,000 rpm for 10 to 30 minutes. 
     
     
         10 . A secondary battery electrode comprising the cathode active material composite for a battery of  claim 1 . 
     
     
         11 . A secondary battery comprising the secondary battery electrode of  claim 10  as a cathode thereof. 
     
     
         12 . The cathode active material composite for a battery of  claim 1 , wherein a compressive strength of the cathode active material composite is equal to or greater than 68 MPa.